looks really nice, the only thing i would say need touch ups would be the spartan's outline, might want to drop shadow it or emboss, something to give it more definition
Really my point of view it looks really nice, for a first try, it's much better than some i've seen in the past. My only suggestion is that you fill the middle blue area with something, it seems kinda empty, but the over all design, I'd give it 7.5/10